1. Field of the Invention
The present invention relates to an exhaust heat recovery apparatus that recovers exhaust heat of an exhaust passage of an internal combustion engine, factory exhaust heat, or the like.
2. Description of the Related Art
There exists an exhaust heat recovery apparatus that recovers the exhaust heat of, for example, an internal combustion engine installed in a vehicle such as car, bus, and truck, and factory exhaust heat, by using the heat engine. An example of the exhaust heat recovery apparatus mentioned above is a stirling engine, which has excellent theoretical heat efficiency. Japanese Patent Application Laid-Open (JP-A) No. H04-089836 discloses an a-type stirling engine of a V-type two-cylinder in which both cylinders are connected by a heat-conducting pipe. JP-A No. S58-192951 discloses a heat gas engine in which a heater is arranged inside a combustion chamber provided with a burner.
However, according to the a-type stirling engine disclosed in JP-A No. H04-089836, a deformation of the heat-conducting pipe, which is used as the heater, due to heat expansion may affect a cylinder connected to the heat-conducting pipe and a piston that reciprocates inside the cylinder. Also, according to the heat gas engine disclosed in JP-A No. S58-192951, a deformation of a heater tube, which constitutes the heater, due to heat expansion may affect the cylinder connected to the heater tube and the piston that reciprocates inside the cylinder. Further, in the heat gas engine disclosed in JP-A No. S58-192951, two cylinders are directly attached to the combustion chamber. Therefore, in these engines, the deformation caused by the heat expansion of the heat-conducting pipe, heater, or combustion chamber changes the distance between the cylinders. The change in the distance influences the reciprocating motion of the piston inside the cylinder, resulting in increases in friction and abrasion in the cylinder.